请参考:非确定的行列转换t1
a b c
1 1 1
1 1 2
1 1 4
1 2 2
1 2 3
2 5 2
2 5 1
2 5 9得到表t2
a b c1 c2 c3 c4
1 1 1 2 4 null
1 2 2 3 null null
2 5 2 1 9 nulldeclare @int int ,@a int,@b int,@sql varchar(8000)
select * ,0 i into #temp from t1
update #temp
set @int=case when @a=a and @b=b then @int +1 else 1 end,
@a=a,@b=b,@i=@intset @sql='select a,b ,'
select @sql=@sql+'sum(case i when '''+cast(i as varchar)+''' then s2 else null end) s'+cast(i as varchar)+',' from (select distinct i from #temp)a
select @sql=left(@sql,len(@sql)-1)+ ' from #temp group by a,b'
exec (@sql)
有时候需要旋转结果以便在水平方向显示列,而在垂直方向显示行。这就是所谓的创建 PivotTable®、创建交叉数据报表或旋转数据。假定有一个表 Pivot,其中每季度占一行。对 Pivot 的 SELECT 操作在垂直方向上列出这些季度:Year Quarter Amount
---- ------- ------
1990 1 1.1
1990 2 1.2
1990 3 1.3
1990 4 1.4
1991 1 2.1
1991 2 2.2
1991 3 2.3
1991 4 2.4生成报表的表必须是这样的,其中每年占一行,每个季度的数值显示在一个单独的列中,如:Year
Q1
Q2
Q3
Q4
1990
1.1
1.2
1.3
1.4
1991
2.1
2.2
2.3
2.4
下面的语句用于创建 Pivot 表并在其中填入第一个表中的数据:USE Northwind
GOCREATE TABLE Pivot
( Year SMALLINT,
Quarter TINYINT,
Amount DECIMAL(2,1) )
GO
INSERT INTO Pivot VALUES (1990, 1, 1.1)
INSERT INTO Pivot VALUES (1990, 2, 1.2)
INSERT INTO Pivot VALUES (1990, 3, 1.3)
INSERT INTO Pivot VALUES (1990, 4, 1.4)
INSERT INTO Pivot VALUES (1991, 1, 2.1)
INSERT INTO Pivot VALUES (1991, 2, 2.2)
INSERT INTO Pivot VALUES (1991, 3, 2.3)
INSERT INTO Pivot VALUES (1991, 4, 2.4)
GO下面是用于创建旋转结果的 SELECT 语句:SELECT Year,
SUM(CASE Quarter WHEN 1 THEN Amount ELSE 0 END) AS Q1,
SUM(CASE Quarter WHEN 2 THEN Amount ELSE 0 END) AS Q2,
SUM(CASE Quarter WHEN 3 THEN Amount ELSE 0 END) AS Q3,
SUM(CASE Quarter WHEN 4 THEN Amount ELSE 0 END) AS Q4
FROM Northwind.dbo.Pivot
GROUP BY Year
GO该 SELECT 语句还处理其中每个季度占多行的表。GROUP BY 语句将 Pivot 中一年的所有行合并成一行输出。当执行分组操作时,SUM 聚合中的 CASE 函数的应用方式是这样的:将每季度的 Amount 值添加到结果集的适当列中,在其它季度的结果集列中添加 0。如果该 SELECT 语句的结果用作电子表格的输入,那么电子表格将很容易计算每年的合计。当从应用程序使用 SELECT 时,可能更易于增强 SELECT 语句来计算每年的合计。例如:SELECT P1.*, (P1.Q1 + P1.Q2 + P1.Q3 + P1.Q4) AS YearTotal
FROM (SELECT Year,
SUM(CASE P.Quarter WHEN 1 THEN P.Amount ELSE 0 END) AS Q1,
SUM(CASE P.Quarter WHEN 2 THEN P.Amount ELSE 0 END) AS Q2,
SUM(CASE P.Quarter WHEN 3 THEN P.Amount ELSE 0 END) AS Q3,
SUM(CASE P.Quarter WHEN 4 THEN P.Amount ELSE 0 END) AS Q4
FROM Pivot AS P
GROUP BY P.Year) AS P1
GO带有 CUBE 的 GROUP BY 和带有 ROLLUP 的 GROUP BY 都计算与本例显示相同的信息种类,但格式稍有不同。
set @sql = 'select department'
select @sql = @sql + ',sum(case goodsname when '''+goodsname+''' then quantity else 0 end) as '+goodsname
from (select distinct goodsname from 有一表) as a
select @sql = @sql+' from 有一表 group by department'exec(@sql)
go
create table #a (department nvarchar(50),goodsname nvarchar(50),quantity int)
insert into #a values ('部门M','货品A',100)
insert into #a values ('部门M','货品B',200)
insert into #a values ('部门N','货品C',200)
insert into #a values ('部门N','货品B',5)
declare @sql varchar(8000)
set @sql = 'select department ,'
select @sql = @sql + 'sum(case goodsname when '''+goodsname+'''
then quantity else 0 end) as '+goodsname+','
from (select distinct goodsname from #a ) as a
select @sql = left(@sql,len(@sql)-1) + ' from #a group by department'exec(@sql)
drop table #a
go
insert into @ values('部门M' , '货品A' , '100')
insert into @ values('部门M' , '货品B' , '3000')
insert into @ values('部门N' , '货品C' , '5')
insert into @ values('部门N' , '货品B' , '200')declare @int int ,@a nvarchar(50),@sql varchar(8000)
select * ,0 i into #temp from @ order by goodsname
set @int=1
update #temp
set @int=case when @a<>goodsname then @int +1 else @int end,
@a=goodsname,i=@int
set @sql='select department,'
select @sql=@sql+'sum(case i when '''+cast(i as varchar)+''' then quantity else null end) 货品'+cast(i as varchar)+',' from (select distinct i from #temp)a
select @sql=left(@sql,len(@sql)-1)+ ' from #temp group by department'
exec (@sql)drop table #temp